#pragma once

#include <iostream>
#include <vector>
#include <pthread.h>
#include <queue>
#include <unistd.h>


struct ThreadInfo
{
    pthread_t tid;
    std::string name;
};

static const int defaultnum = 5;

template <class T>
class ThreadPool
{
    
public:
    void Lock()
    {
        pthread_mutex_lock(&mutex_);
    }
    void UnLock()
    {
        pthread_mutex_unlock(&mutex_);
    }
    void WakeUp()
    {
        pthread_cond_signal(&cond_);
    }
    void ThreadSleep()
    {
        pthread_cond_wait(&cond_,&mutex_);
    }

    bool IsQueueEmpty()
    {
        return tasks_.empty();
    }

    std::string GetThreadName(pthread_t tid)
    {
        for (const auto& ti : threads_)
        {
            if (ti.tid == tid)
            {
                return ti.name;
            }
        }

        return "None";
    }

    static ThreadPool<T>* GetInstance()
    {  
        if (nullptr == tp_) 
        {
            pthread_mutex_lock(&lock_);
            if (tp_ == nullptr)
            {
                std::cout << "log: singletion create done first!" << std::endl;
                tp_ = new ThreadPool<T>;
            }
            pthread_mutex_unlock(&lock_);
        }

        return tp_;
    }

public:  
    static void* HandlerTask(void* args)
    {
        ThreadPool<T>* tp = static_cast<ThreadPool<T>*>(args);
        std::string name = tp->GetThreadName(pthread_self());

        while (true)
        {
            tp->Lock();

            while (tp->IsQueueEmpty())
            {
                tp->ThreadSleep();
            }

            T t = tp->Pop();

            tp->UnLock();

            t();
        }
    }

    void Start()
    {
        int num = threads_.size();
        for (int i = 0; i < num; i++)
        {
            threads_[i].name = "thread-" + std::to_string(i + 1);
            pthread_create(&(threads_[i].tid),nullptr,HandlerTask,this);
        }
    }

    T Pop()
    {
        T t = tasks_.front();
        tasks_.pop();

        return t;
    }

    void Push(const T& t)
    {
        Lock();
        tasks_.push(t);
        WakeUp();
        UnLock();
    }

    ~ThreadPool()
    {
        pthread_mutex_destroy(&mutex_);
        pthread_cond_destroy(&cond_);
    }
private:
    ThreadPool(int num = defaultnum)
        :threads_(num)
    {
        pthread_mutex_init(&mutex_,nullptr);
        pthread_cond_init(&cond_,nullptr);   
    }

    ThreadPool(const ThreadPool<T>&) = delete;
    ThreadPool<T>& operator=(const ThreadPool<T>&) = delete;

private:
    std::vector<ThreadInfo> threads_;
    std::queue<T> tasks_;

    pthread_cond_t cond_;
    pthread_mutex_t mutex_;

    static ThreadPool<T>* tp_;

    static pthread_mutex_t lock_;
};

template<class T>
ThreadPool<T>* ThreadPool<T>::tp_ = nullptr;

template<class T>
pthread_mutex_t ThreadPool<T>::lock_ = PTHREAD_MUTEX_INITIALIZER;